Cord Blood Gas Results | What You Need to Know
If you're an expecting mother, you may have heard about umbilical cord clamping after birth. Clamping the umbilical cord is standard procedure when a baby is born.
This procedure is actually a vital component of determining the health of your baby by using cord blood gases to detect if they suffered a birth injury during delivery. Cord blood gases show whether or not a baby is experiencing acidosis, which can indicate that there was a hypoxic ischemic event. The results from cord blood gases are frequently used as evidence in medical malpractice lawsuits by both attorneys and doctors as a marker for the harm done to the child and to prove whether negligence was involved in a child's injury.
To understand what cord blood gases are, it's helpful to know how the placenta supplies oxygen and nutrition to a baby in the womb. A fetus relies on the mother for oxygen and carbon dioxide exchange. A developing baby does not breathe in the same way they would after birth. The placenta uses gas exchange to supply them with oxygen that comes from the mother's blood. After the mother's blood is oxygenated, it is absorbed by the placenta's capillaries. The capillaries will then deliver the blood to the placenta's main artery where it is finally transferred to the baby.
When the baby is born, the umbilical artery briefly retains information about the baby's current condition, referred to as blood cord gases. Doctors clamp the umbilical cord within seconds after birth to be able to measure the level of acidity inside the umbilical artery.
The question is how much oxygen the baby was getting. Cord blood gas analysis is the best indicator of hypoxia or ischemia during the delivery period.
The results of the analysis can show how healthy the baby is and determine if they have a birth injury.
It is also important to get accurate results. This is why the cord must be clamped quickly. Waiting even 45 seconds will skew the results due to chemicals changing in the artery.
The base deficit is calculated using measured blood levels for acid (pH), dissolved cardon dioxide gas (PCO2) and bicarbonate HCO. It these values that we are talking about that together describe the baby's metabolic state.
The doctor will clamp the umbilical cord quickly after childbirth. A needle withdraw blood that is in the cord. Again, this needs to be done quickly to get reliable cord blood gas results.
The most important measurements used in cord blood gases examination are the baby's pH levels and their base deficit. Both are used to determine the acidity level in the umbilical cord. The levels determine if the baby has acidosis, a condition caused by the overproduction of acid in the blood. Acidosis usually presents itself as decreased blood pH and increased base deficit. If a baby has acidosis, it's a major red flag that indicates the presence of hypoxia during delivery.
Normal blood cord gases levels in a full-term newborn:
- Mean pH: 7.28 ± 0.07
- Mean PCO2 (carbon dioxide): 49.9 ± 14.2 (mmHg)
- Mean PO2 (oxygen): 23.7 ± 10.0 (mmol/L)
- Mean base deficit: -3.6 ± 2.8 (mmol/L)
Normal blood cord gases levels in a preterm newborn:
- Mean pH: 7.29 ± 0.07
- Mean PCO2: 49.2 ± 9.0 (mmHg)
- Mean PO2: 23.6 ± 8.9 (mmol/L)
- Mean base deficit: -3.3 ± 2.4 (mmol/L)
All values are ± 1 standard deviation. The "P" in PO2 and PCO2 means "partial pressure", which how the cord blood gases are measured. PCO2 measures the amount of carbon dioxide gas dissolved in the blood, and PO2 measures how much oxygen is in the blood.
Cord pH provides and important measurement of the acid base status of the baby at the moment that the cord was cut. This give us a good window into the oxygenation status of the fetus in the immediate period leading up to delivery.
Acidosis has two different types: respiratory acidosis and metabolic acidosis. Respiratory acidosis refers to high acid levels caused by impaired lung function, leading to retained carbon dioxide in the lungs and bloodstream. Metabolic acidosis is when there are high acid levels in the body that originated from impaired kidney function. Both forms of acidosis can cause neurological issues that can be temporary or permanent depending on how severe the damage is. In general, however, metabolic acidosis is associated with more adverse outcomes.
Low pH levels caused by acidosis can result in hypoxic-ischemic encephalopathy, periventricular leukomalacia, seizures, brain hemorrhages, and cerebral palsy. In severe cases of metabolic acidosis, it can lead to multi-organ failure and even death. The primary cause of acidosis comes from the lack of adequate oxygen being transferred from the placenta to the baby.
Blood cord gases results can be used as an important piece of evidence in birth injury litigation. If a baby suffered from hypoxia that resulted in a birth injury, the blood cord gases can prove the legitimacy of the plaintiff's claim. It can also be used to show the severity of damage that occurred during delivery by citing the specific pH and base deficit levels. However, doctors can also use blood cord gases to their own advantage as well. If the baby has a birth injury but their blood cord gases came back normal, the defendant doctor can use it as evidence to prove that the injury did not occur during delivery and therefore was not caused by negligence.
There are many reasons as to why a baby would have normal blood cord gases despite suffering from a hypoxic brain injury. The baby might have had poor circulation and perfusion shortly before being born, they could have experienced a physical head injury during delivery, or there may have been an error in the process of storing and analyzing the blood. According to one study, up to 19% of blood cord gases samples are invalid due to human error.
In order to prevail in a birth injury case involving blood cord gases, an attorney needs to be skilled in their medical knowledge about pH and base deficit levels. They should take the time to examine the process of taking blood cord gases samples and identify any possible technical errors that make the results invalid. It's also beneficial to work closely with a medical expert to be able to find the cause and timing of the birth injury.
Abnormal cord blood gas results are a marker for a birth injury But abnormal cord blood gas results do not mean that you child has a brain injury. Many child has troubling cord blood gas and APGAR results and have no physical or cognitive deficits.